why no HT fuse on the express?

[Roe]

would it be an good idea to add a 500ma hf fuse on an express?

[rooster]

Hey. No not on my Express but on my Rocket and AC30 clone. My reasoning might not be sound but AC30s are known to burn up the OT back in the day. This probably had more to do with the beeswax potted trannys, the paper bobbins and paper coil wraps, but I just do it anyway.

Many people are all over fusing the OT so its your call. Yes, 500ma is probably right. The best way to do this is sample them in 100ma values starting at 300ma - or just use the 500. I can tell you that an AC30 will take out a 1 amp fuse just as quickly as a 500ma one if you have a problem with the EL84 quad. So I think it is safe to say you have a little wiggle room.